Friday, June 12, 2009

H1N1 swine flu was officially declared a pandemic by the World Health Organization (WHO) yesterday, Thursday, June 11, 2009, describing it as a "moderate" pandemic. The reasons for the declaration, per the WHO website:

On the basis of available evidence and expert assessments of the evidence, the scientific criteria for an influenza pandemic have been met. The Director-General of WHO has therefore decided to raise the level of influenza pandemic alert from phase 5 to phase 6. [link]

As of 07:00 GMT, 12 June 2009, total global laboratory-confirmed cases of new influenza A(H1N1) as officially reported to WHO by States Parties to the International Health Regulations (2005) were at 29,669 cases. [link]

What Makes H1N1 Potentially More Dangerous Than Ordinary Flu?

Considering ordinary flu during peak flu seasons account for up to 500,000 deaths per year [link], what makes the new influenza A (H1N1) -- with only 145 confirmed deaths to date -- such a major concern?

There are a few reasons, actually, including...

First, the age and health of some victims. Where most flu viruses tend to be particularly dangerous for the weak, young and the elderly, this particular strain appears to be striking in even healthy individuals and in age ranges generally considered low risk for death from flu viruses.

For example, even though the virus appears to be slowing in the USA, on Thursday three additional deaths from H1N1 were reported in New York -- including a child under 2, a teenager and a person in their 30s.

Second, the virus is spreading from person to person during non-flu season. Had it spread during regular flu season, it could have been far worse, as we find in the third point...

Third, perhaps the most important, there is the very real fear that H1N1 could mutate into something far more dangerous now that it is passing so quickly and easily from person to person.

In humans - if a person who already has flu is comes into close contact with birds who have highly pathogenic avian flu, there is a tiny chance that the person could become infected with the avian flu virus. If this happens, the person would now be carrying both the human flu virus and the avian flu virus. The two viruses could meet in the person's body and swap genes with each other. If the new virus had the avian flu's genes that made it rapidly fatal and the human flu's genes to allow it to be passed from person to person, a flu pandemic could result.

In pigs - pigs are susceptible to both human and bird flu viruses. If a pig became infected with both viruses at the same time, it could act as a "mixing vessel", allowing the two viruses to swap genes and produce a new virus.

With H1N1, the mutation process is the same. With H1N1, however, we already have widespread, fast human to human transmission... The very real danger now becomes a mutation as a result of someone infected with another virus becoming infected with this particular strain.

Keeping in mind that the World Health Organization states "the pandemic is only 'moderate in severity' and cautions against overreaction by the public" ...there is another take from experts:

Experts fear, however, that as it passes through populations, it could mutate to become more lethal and return with increased force in the winter influenza season. That is what happened with the Spanish flu pandemic of 1918. [link]

What are the 6 phases of a pandemic?

PHASE 1 - 3: Predominantly animal infections - few human infections.

PHASE 4: Sustained human to human infection.

PHASE 5 - 6: Widespread human infection.

There are two additional non-numbered phases to a pandemic by WHO definition, and they are, in order:

As they write in their media release upgrading H1N1 to Phase 6 (pandemic status), "We know, too, that this early, patchy picture can change very quickly. The virus writes the rules and this one, like all influenza viruses, can change the rules, without rhyme or reason, at any time." [link]

For now, at least, H1N1 is only "moderate in severity" ...let's all hope it stays that way.